During 1972 an historical-prospective study of long-term complications of induced abortion was conducted in Skopje, Yugoslavia, in which pregnancy histories of 948 women were collected and analyzed. Typical results to date are: (a) for this sample there was no increase in first-birth prematurity when the women had a prior induced abortion; (b) among contraceptors, those whose preceding pregnancy was not artificially aborted had better subsequent pregnancy outcomes than did aborters; (c) 13.2% of those women who used induced abortion for family size limitation experienced a premature pre-abortion delivery as compared to 3.8% prematurity for those who subsequently used induced abortion to space their children; and (d) there is not a significant difference in time to next delivery for aborters and non-aborters as measured by a Markov Chain developed for this data set. Additional proposed analysis will address contraceptive usage patterns, inter-pregnancy intervals, and smoking patterns through Markov chain analysis. A semi-Markov model will be compared to the Markov Chain to test for increased efficiency and ease of application for this type of study. The utilization of Markov Chains for this epidemiological research will be explored relative both to life table techniques and to categorical methods, the latter in regards to sample size determination in retrospective and prospective studies.